What is the difference between present perfect and past perfect?

Related questions

1. Where do we use past simple and past perfect?
2. What is present perfect tense in German?
3. When use the present perfect tense?
4. What is difference between present perfect and present perfect continuous?
5. What is perfect participle?
6. What is present perfect tense and past perfect tense?
7. What is the rule of present perfect?
8. What are the 3 aspects of verb?
9. What is the example of present perfect continuous tense?
10. Why is the perfect tense called perfect?

Tags

1. #combining
2. #event
3. #present
4. #however
5. #similar
6. #between
7. #started
8. #events
9. #participle
10. #because
11. #perfect
12. #difference
13. #specified
14. #ended
15. #formed